During communication in a WLAN system, errors of transmitted data bits often occur in a string. However, a channel encoding is only effective when a single error or an error string which is not very long is detected and corrected.
To solve the above mentioned problem, an interleaving processing technology is used to process the transmitted data bits. With the interleaving processing technology adopted, continuous transmitted data bits are dispersed, and the transmitted data bits may be transmitted in a discontinuous mode. Thus, even if a string of errors occurs in a transmission process, when a message of successive bit string is recovered, the errors are changed to single errors (or error strings with a shorter length), and then an error correction function of channel encoding is used to correct errors to recover originally transmitted data bits more precisely.
In 802.11a/g protocols, it is necessary to perform two times of sub-interleaving processing on transmitted data bits; in 802.11n/ac/ah protocols, it is necessary to perform three times of sub-interleaving processing on transmitted data bits; and interleaving processing parameters of any sub-interleaving processing may be determined by the number of data sub-carriers, i.e., when the number of data sub-carriers changes, the interleaving processing parameters need to be changed accordingly.
Additionally, the 802.11a/g/n/ac/ah protocols adopt an OFDM (Orthogonal Frequency Division Multiplexing, Orthogonal Frequency Division Multiplexing) technology for data transmission. The OFDM is a multi-carrier technology, which divides a frequency domain into several mutually orthogonal data sub-carriers, and maps modulation signals corresponding to the transmitted data bits after the interleaving processing and modulation onto the corresponding data sub-carriers for transmission respectively, and the number of data sub-carriers is fixed.
After the last sub-interleaving processing is performed, the output data bits to be transmitted may be modulated to obtain modulation signals, and then the modulation signals are mapped onto the corresponding data sub-carriers for transmission.
In the process of achieving the above mentioned interleaving processing, the inventor found that at least the following problems exist in the prior art: when frequency selective fading of a channel is serious, selecting a part of data sub-carriers for transmission may further improve system performance; however, when the number of data sub-carriers changes, the parameters for performing interleaving processing in an interleaver also need to be changed, and the interleaver in an actual chip implementation is fixed through hardware. Therefore, when the number of data sub-carriers changes, the parameters for performing interleaving processing in the interleaver need to be modified by modifying hardware, thus resulting in a high cost.